Electromagnetic Mass in (n+2)(n+2) Dimensional Space-times

Einstein-Maxwell field equations correspoding to higher dimensional description of static spherically symmetric space-time have been solved under two specific set of conditions, viz., (i) $\rho \ne 0$, $\nu^\prime= 0$ and (ii) $\rho=0$, $\nu^\prime\ne 0$ where $\rho$ and $\nu$ represent the mass density and metric potential. The solution sets thus obtained satisfy the criteria of being electromagnetic mass model such that the gravitational mass vanishes for the vanishing charge density $\sigma$ and also the space-time becomes flat. Physical features related to other parameters also have been discussed.Comment: 4 Latex pages in Revtex4 styl

Lorentz's electromagnetic mass: a clue for unification?

We review in the present article the conjecture of electromagnetic mass by Lorentz. The philosophical perspectives and historical accounts of this idea are described, especially, in the light of Einstein's special relativistic formula {E = mc^2}. It is shown that the Lorentz's electromagnetic mass model has taken various shapes through its journey and the goal is not yet reached.Comment: 11 pages, 0 figur

A class of solutions for Einstein field equations with spatially varying cosmological constant in spherically symmetric anisotropic source

In this work a class of interior solution for Einstein field equations corresponding to a spherically symmetric anisotropic fluid sphere has been obtained under the assumption that the cosmological constant is spatially variable. The solution obtained has the characteristics that the pressure and the cosmological parameter vanish at the centre and at the boundary with a maximum value somewhere inside the body. It has been argued that a variable $\Lambda$ is as much important physically in Astrophysics as in Cosmology.Comment: 5 Latex page

N.C. Rana: The Life of a `Comet' in the Astrophysical World

Narayan Chandra Rana, a person with extraordinary potential from a remote village of Bengal, India, came into the limelight of the international scientific world through his exceptional talent, zeal and courage. In his very short life-span, he excelled not only into various branches of astrophysics, but also took a leading role in science popularization, text book writing etc. In this paper, life and works of that budding scientist of India have been discussed from multifarious viewpoints.Comment: 24 pages, 18 figure

Dark Energy Models With Variable Equation Of State Parameter

Two variable $\Lambda$ models, viz. $\Lambda \sim (\dot a/a)^2$ and $\Lambda \sim \rho$ have been studied under the assumption that the equation of state parameter $\omega$ is a function of time. The selected $\Lambda$ models are found to be equivalent both in four and five dimensions. The possibility of signature flip of the deceleration parameter is also shown.Comment: 15 Latex pages, a few changes in the text. Accepted in IJMP

Inflationary phase and role of dark energy: Revisited

The inflationary phase of the Universe is explored by proposing a toy model related to the scalar field, termed as {\it inflaton}. The potential part of the energy density in the said era is assumed to have a constant vacuum energy density part and a variable part containing the inflaton. The prime idea of the proposed model constructed in the framework of the closed Universe is based on a fact that the inflaton is the root cause of the orientation of the space. According to this model the expansion of the Universe in the inflationary epoch is not approximately rather exactly exponential in nature and thus it can solve some of the fundamental puzzles, viz. flatness as well as horizon problems. It is also predicted that the constant energy density part in the potential may be associated to the dark energy, which is eventually different from the vacuum energy, at least in the inflationary phase of the Universe. However, the model keeps room for the end of inflationary era.Comment: 6 pages, 1 figure, Major changes in the assumption and textual versio

Searching for a Solution to the Age Problem of the Universe

We present here a phenomenological cosmological model under perfect fluid distribution with a stiff equation of state $p=\rho$. The erstwhile cosmological constant is assumed to be a time dependent variable, i.e., $\Lambda = \Lambda(t)$ in our study. It has been shown that the estimates of different cosmological parameters from this model are in good agreement with the experimental results, especially 13.79 Gyr as the age of the universe is quite satisfactory. The behavior and relation of $\Lambda$-stiff fluid model with dust, viscous fluid and variable $G$ have also been investigated in detail.Comment: 5 LaTex pages, considerable changes in the text and also addition of new references. Accepted for publication in Gravitation and Cosmolog

A Note On Astronomer R. G. Chandra and British Astronomical Association

In the present Note we have presented some documents to reveal the longstanding relationship of Indian amateur astronomer R. G. Chandra with British Astronomical Association.Comment: 8 Latex page

A Village Astronomer: Life and Works of R. G. Chandra

In the present article we provide a brief introduction to the Life and Works of Indian astronomer R. G. Chandra.Comment: 29 Latex page

Relativistic Electromagnetic Mass Models With Cosmological VariableΛ\Lambda in Spherically Symmetric Anisotropic Source

A class of exact solutions for the Einstein-Maxwell field equations are obtained by assuming the erstwhile cosmological constant $\Lambda$ to be a space-variable scalar, viz., $\Lambda =\Lambda(r)$. The source considered here is static, spherically symmetric and anisotropic charged fluid. The solutions obtained are matched continuously to the exterior Reissner-Nordstr\"{o}m solution and each of the four solutions represents an electromagnetic mass model.Comment: 10 Latex page